They were scared in 16 but they aren't now. My guess is they know the people in Bernie's orbit pretty well and have ascertained that there is only one of him in his campaign, possibly working in tandem with his staff union
I'm increasingly convinced that the biggest material concession the ruling class left has extracted from Sanders is the one they will count on to bring him down in the general and to weigh him down if he wins (Bernie keeps promises and the deportation freeze is possible day 1)